20-year-old Lanza firing at students and staff with a powerful military-style rifle, according to police, before killing himself with a handgun.

Police also confirmed that Lanza had shot his mother, Nancy, dead in her home before the attack.

All of the murdered children were either six or seven-years-old, feeding more emotion into a revived debate about whether stricter gun laws could prevent future mass shootings in the US.

Olivia Engel, 6, had a part in a nativity play at St Rose of Lima Catholic Church.

"She was supposed to be an angel in the play. Now she's an angel up in heaven," Monsignor Robert Weiss told a standing-room-only crowd at the church before the play yesterday.

Emilie Parker, 6, another of the child victims, was studying Portuguese with her father.

Victoria Leigh Soto, 27, saved her first-grade students' lives by putting herself between the children and the gunman.

School district officials said classes would resume Tuesday, except for Sandy Hook – where they are working on a plan for how and where to let the school's kindergarten-through-4th-grade classes resume.

During his time in Connecticut, Mr Obama will be watched closely for clues as to what he meant when he called for "meaningful action" to prevent such tragedies in the wake of the massacre on Friday.

Though Americans have seen many mass shootings in the past decades, the victims have rarely been so young.

Some Democratic lawmakers called for sweeping new gun-control measures, a move certain to run up against stiff opposition from the nation's powerful pro-gun lobby.

While the president and families mourn, police are still pushing for a fuller explanation of what drove Lanza, 20, to kill his mother at her house, go to Sandy Hook Elementary, shoot out a window and storm through the school with multiple weapons.

Police earlier said they had assembled "some very good evidence" on the killer's motives.

Nancy Lanza legally owned a Sig Sauer and a Glock, both handguns commonly used by police, and a military-style Bushmaster .223 M4 carbine, according to law enforcement officials.

His father issued a statement saying the family was in a "state of disbelief."

Pope Benedict expressed his pain over the killings, telling crowds of pilgrims gathered in St Peter's Square that he was "deeply saddened."

"I assure the families of the victims, especially those who lost a child, of my closeness in prayer. May the God of consolation touch their hearts and ease their pain," the Pope said.

"Upon those affected by this tragedy, and upon each of you, I invoke God's abundant blessings".

The other adult victims of the shooting were named as teacher Lauren Rousseau, 30; school psychologist Mary Sherlach, 56; school principal Dawn Hochsprung 47; teacher Anne Marie Murphy, 52.